1. Field of the Invention
The present invention relates generally to turbomachinery and, more particularly, to an instrumentation probe for use within a turbomachine.
2. Description of the Prior Art
The measurement of physical properties of fluids such as temperatures and pressures is routinely required for properly controlling the operation of sophisticated turbomachinery such as gas turbine engines. Instrumentation probes, such as the Temperature Sensor Probe described and claimed in U.S. Pat. No. 3,451,862, have been utilized to make such physical property measurements.
Prior art gas turbine engines have employed numerous such instrumentation probes independently mounted on an engine casing and extending into the engine gas flow at various axial engine locations having relatively unobstructed gas flow, such as structural frame elements. For example, in one family of fan jet engines, the exhaust gas temperatures and pressures are sensed by probes located in a structural frame which couples the high pressure turbine to the low pressure turbine.
Although the prior art approach has had generally satisfactory results, the independently mounted probes tend to produce aerodynamic separation and wakes in the gas stream which decrease the overall efficiency of the engine. In addition, in the development of some modern gas turbine engines, efficiency improvement programs have resulted in the elimination of unnecessary weight, including some of the structural frames upon which the prior art instrumentation was mounted. For example, in one such engine the structural frame which couples the high pressure turbine to the low pressure turbine has been eliminated and the two turbines have been moved closer together. In this engine, it is not practical to place an exhaust gas temperature or pressure probe in the free stream space between the two turbines since to do so may result in pressure pulses which would be reflected upstream upon the high pressure turbine rotating blades. It is also undesirable to axially shift the location of such an exhaust gas probe since the probe must remain in the same precise axial location in order to maintain a high level of sensitivity.